Biology subjects

Morris, E. M. M.

Publications and source records attributed to Morris, E. M. M..

7 recordsLinked to original sources

bioRxiv2026

Hepatocyte Estrogen Receptor α Mediates Estrogen-induced Augmentation of Hepatic 1 Mitochondrial Respiration Following Ovariectomy.

Whole-body estrogen receptor (ER) knockout mice develop hepatic steatosis; however, liver-specific ER knockout (LERKO) mice fail to recapitulate this susceptibility and maintain normal hepatic mitochondrial function. However, estrogen-mediated protection against hepatic steatosis is lost in LERKO mice following ovariectomy (OVX). Here, we tested whether loss of hepatic ER blunts estrogen modulation of hepatic mitochondrial respiratory capacity and mitochondrial proteome following ovariectomy (OVX). Sham or ovariectomy (OVX) surgery was performed in middle-aged female mice (36-40 weeks), followed by AAV injection to generate Control (Con; GFP) or LERKO mice (Cre). All mice were placed on a high-fat diet (HFD) for 10 weeks following surgery. Half of the OVX mice received 17-beta estradiol (E2) replacement (OVX+E2) for the last 4 weeks of HFD. OVX mice had greater body mass and adiposity, which was reversed by E2 replacement in both Con and LERKO mice. While E2 replacement reduced steatosis in both Con and LERKO OVX mice, the LERKO OVX mice maintained greater hepatic triglyceride content. E2 replacement promoted greater basal and ADP-stimulated (State 3) mitochondrial respiration in Con OVX but not in LERKO OVX mice under palmitate-supported conditions. Changes in mitochondrial respiration could not be attributed to altered responses to changes in energy demand (GATP) or to alterations in mitochondrial H2O2 production. Conversely, maximal coupled branched-chain amino acid-supported respiration was universally suppressed by E2 replacement. Proteomics analysis revealed E2-mediated reductions in hepatic mitochondrial energy transduction, with relatively minimal differences between Con and LERKO mice. In conclusion, post-ovariectomy estrogen treatment reduces steatosis in the absence of hepatic ER; however, triglyceride levels remain higher, and mitochondrial respiratory deficits persist despite similar proteomic signatures, suggesting that ER signaling is required for optimal estrogen hepatic responsiveness.

biochemistry↗

bioRxiv2025

The Impact of a Western Diet with High Salt on Metabolic Outcomes in Male C57bl/6J Mice

ObjectiveThe Western diet promotes obesity and metabolic disease by increasing caloric intake and systemic inflammation. The typical Western diet is high in saturated fats, sugars, and salt. In pre-clinical rodent studies, the "Western" diet (also called the high-fat high-sucrose diet (HFHS)) is high in saturated fats and sugars (typically sucrose) but low in salt (<1% salt). As such, we sought investigate the impact of a chronic 3% NaCl Western diet (high-fat, high-sucrose + high salt (HFHS + Salt)) diet on systemic organ metabolism, liver mitochondrial function, and adipose tissue. MethodsThirty-six 8 week-old C57Bl/6J male mice were fed either a low-fat diet (LFD), a HFHS, or a HFHS + Salt diet for 16 weeks. Body weight, body composition, and food intake were monitored weekly. Glucose tolerance tests (GTT) and insulin concentrations were measured after 8 weeks of diet intervention to assess glucose and insulin homeostasis. Mice were euthanized at 16 weeks for liver mitochondrial respiration and tissue analysis. ResultsOver 16 weeks, the HFHS fed group gained significantly more weight than the other diet groups. Liver weights were similar in LFD and HFHS + Salt groups but higher in the HFHS group. Liver triglycerides (TAGs) were also similar between LFD and HFHS + Salt groups, while HFHS had elevated liver TAGs. Inguinal and brown adipose tissue depots were larger in both HFHS and HFHS + Salt vs. LFD. Surprisingly, the gonadal adipose tissue was significantly larger in the HFHS + Salt compared to HFHS and LFD groups - suggesting that a HFHS + Salt exacerbates gonadal adipose expansion more than typical rodent HFHS. Paradoxically, the addition of salt appears to have dampened expression of inflammation related genes (Ccl2 & Adgre1) in adipose tissue compared to HFHS alone. Metabolically, the HFHS+ Salt fed mice showed the highest glucose intolerance, followed by HFHS and then LFD groups. Liver mitochondrial respiration, assessed by changing ATP/ADP ratios, showed the HFHS group with the highest oxygen consumption, followed by HFHS + Salt, then LFD groups, highlighting differences in respiration with additional salt (HFHS vs HFHS + Salt). ConclusionWhile the excess salt mitigated some HFHS effects on weight gain and hepatic lipid accumulation, it exacerbated gonadal adipose expansion and impaired glucose tolerance. HFHS increased mitochondrial respiration, but salt addition appeared to dampen this effect. Dietary salt, within a high-fat/high-sucrose context, has differential impacts on metabolic outcomes compared to HFHS alone, underscoring the need for further research to fully understand how Western diets (high-fat, high-sucrose, and high salt) impact all aspects of metabolic health.

physiology↗

bioRxiv2025

Hepatic ketogenic insufficiency blunts exercise-induced energy expenditure and alters mitochondrial proteins in skeletal muscle.

Ketone body (KB) utilization increases during fasting and exercise due to enhanced hepatic fatty acid oxidation and KB production via the rate-limiting mitochondrial enzyme hydroxymethylglutaryl-CoA synthase (HMGCS2). Since KB metabolism intersects with multiple metabolic pathways, and skeletal muscle KB catabolism rises during exercise, we tested the hypothesis that liver-specific HMGCS2 knockouts (KO) would have reduced energy expenditure (EE) and changes in the mitochondrial proteome of skeletal muscle with chronic exercise through voluntary wheel running (VWR), time-restricted feeding (TRF), or both combined to boost hepatic KB production and utilization. Control (CON) and HMGCS2 knockout (KO) mice (n=6-8 per group) underwent sedentary ad libitum feeding (SED+AL), SED+TRF, VWR+AL, and VWR+TRF for 16 weeks, with whole-body EE measured using indirect calorimetry. In CON mice, VWR increased total EE by 19.5% and non-resting EE by 50% under AL conditions, and total EE by 16% and non-resting EE by 47.9% under TRF conditions. However, the EE increases seen with VWR did not occur in KO mice. Proteomic analysis revealed that the loss of liver HMGCS2 significantly impacted proteins involved in metabolic processes within skeletal muscle, including reduced oxidative phosphorylation (OXPHOS) protein expression in SED KO mice compared to sedentary CON. Notably, VWR restored OXPHOS protein expression in the muscle of the liver HMGCS2 KO but did not alter it in the CON. Furthermore, muscle from liver HMGCS2 KO mice had elevated expression glycolytic pathways in sedentary and VWR conditions. These results indicate that hepatic ketogenic deficiency (HMGCS2 KO) diminishes exercise-induced increases in EE and uniquely impacts baseline and exercise-related adaptations in the metabolic and mitochondrial proteome of skeletal muscle.

physiology↗

bioRxiv2025

Non-Contrast microCT Analysis of Obese Adipose in Response to Cold-Exposure Reveals Sex-Specific Alterations

In 2020, it was reported that obesity in the United States had increased by 12% from 1999 to 2018. While exercise and diet are optimal lifestyle modifications to curb obesity, drug-based therapeutics focus on glucagon-like peptide (GLP) modifiers. Alternatively, current research suggests that a specialized type of adipose, called thermogenic adipose, may help protect against obesity. Active thermogenic adipose can metabolize free fatty acids (FFAs) and carbohydrates to carry out non-shivering thermogenesis (NST), potentially providing a method for reducing excess energy stores. While brown adipose tissue (BAT) provides the primary thermogenic response, we hypothesized that exposing diet-induced obese (DIO) mice to colder temperatures would also diminish white adipose tissue (WAT) depots and suppress their inflammatory signature. To measure adipose response to cold in vivo, we applied a non-contrast microCT ({micro}CT) imaging analysis. Male and female mice were housed at thermoneutrality (TN) and fed a Western-style diet (WD) ad lib until they became obese. Once they reached this stage, the mice were subjected to a thermalshift (TS) and exposed to either room temperature (RT) of 22{degrees}C or a colder temperature of 18{degrees}C. The adipose response was then assessed in post-exposure tissues by histological analysis, proteomics, and molecular characterization to correlate phenotypic changes with our {micro}CT findings. Results from this analysis revealed a sex-specific response to cold exposure: thermogenic adipose was predominantly formed in the interscapular BAT (iBAT) of male mice, while female mice showed formation in their perigonadal WAT (pgWAT) and iBAT when exposed to 18{degrees}C. Furthermore, male mice exhibited a decline in serum glucose levels when subjected to 18{degrees}C, which was increased in TS female mice. Serum-free fatty acids (FFAs) were unaffected by either sex across different environmental conditions. Importantly, using a mass-spectrometry-based approach, we detected a reduction in pro-inflammatory cytokines in the conditioned media (CM) of pgWAT and iBAT from TS male mice compared to TN DIO male mice. Overall, our studies demonstrated a new {micro}CT-based analytical method to detect changes in obese adipose tissue and highlighted unique sex-specific responses to environmental exposure. Our findings suggest that thermogenic adipose may offer a promising avenue for combating obesity and reducing its pathologic characteristics.

cell biology↗

bioRxiv2020

A high fat anti-inflammatory diet improves widespread allodynia despite worsening metabolic outcomes in adult mice exposed to neonatal maternal separation

Inflammation plays a key role in the progression and maintenance of chronic pain, which impacts the lives of millions of Americans. Despite growing evidence that chronic pain can be improved by treating underlying inflammation, successful treatments are lacking and pharmaceutical interventions are limited due to drug side effects. Here we are testing whether an anti-inflammatory diet (AID) containing a combination of key anti-inflammatory compounds, at clinically relevant doses, improves pain-like behaviors in a preclinical model of chronic widespread hypersensitivity induced by neonatal maternal separation (NMS). Our results demonstrate a benefit of the AID on pain-like behaviors, despite the diet being high in fat, which led to increased caloric intake, adiposity, and weight gain. The AID specifically increased measures of metabolic syndrome and inflammation in female mice, compared to an isocaloric, macronutrient-matched diet lacking the anti-inflammatory compounds. Male mice, especially those exposed to NMS, were equally susceptible to both diets worsening metabolic measures. This work highlights important sexual dimorphic outcomes related to early life stress exposure and dietary interventions, as well as a potential disconnect between improvements in pain-like behaviors and metabolic measures.

physiology↗

bioRxiv2020

Early life stress reduces voluntary exercise and its prevention of diet-induced obesity and metabolic dysfunction in mice

The development of obesity-related metabolic syndrome (MetS) involves a complex interaction of genetic and environmental factors. One environmental factor found to be significantly associated with MetS is early life stress (ELS). We have previously reported on our mouse model of ELS, induced by neonatal maternal separation (NMS), that displays altered regulation of the hypothalamic-pituitary-adrenal (HPA) axis and increased sensitivity in the urogenital organs, which was attenuated by voluntary wheel running. Here, we are using our NMS model to determine if ELS-induced changes in the HPA axis also influence weight gain and MetS. Naive (non-stressed) and NMS male mice were given free access to a running wheel and a low-fat control diet at 4-weeks of age. At 16-weeks of age, half of the mice were transitioned to a high fat/sucrose (HFS) diet to investigate if NMS influences the effectiveness of voluntary exercise to prevent diet-induced obesity and MetS. Overall, we observed a greater impact of voluntary exercise on prevention of HFS diet-induced outcomes in naive mice, compared to NMS mice. Although body weight and fat mass were still significantly higher, exercise attenuated fasting insulin levels and mRNA levels of inflammatory markers in epididymal adipose tissue in HFS diet-fed naive mice. Only moderate changes were observed in exercised NMS mice on a HFS diet, although this could partially be explained by reduced running distance within this group. Interestingly, sedentary NMS mice on a control diet displayed impaired glucose homeostasis and moderately increased pro-inflammatory mRNA levels in epididymal adipose, suggesting that early life stress alone impairs metabolic function and negatively impacts the therapeutic effect of voluntary exercise.

physiology↗

bioRxiv2019

Divergent Energy Expenditure Impacts Mouse Metabolic Adaptation to Acute High-Fat/High-Sucrose Diet Producing Sexually Dimorphic Weight Gain Patterns

ObjectiveLong-term weight gain can result from cumulative small weight increases due to short-term excess caloric intake during weekends and holidays. Increased physical activity may mediate weight gain through increases in energy expenditure (EE) and reductions in energy balance. Current methods for modulating mouse EE (e.g. - exercise, chemical uncouplers, etc.) have confounding effects. However, it is known that mouse EE linearly increases as housing temperature decreases below the thermoneutral zone. MethodsTo determine how robust differences in baseline EE impact 7-day changes in weight and body composition on low-fat and high-fat, high-sucrose (HFHS) diets, we performed indirect calorimetry measurements in male and female mice housed at divergent temperatures (20{degrees}C vs. 30{degrees}C). ResultsAs expected, mice housed at 30{degrees}C have [~]40% lower total EE and energy intake compared to 20{degrees}C mice regardless of diet or sex. Energy balance was increased with HFHS in all groups, with [~]30% greater increases observed in 30{degrees}C versus 20{degrees}C mice. HFHS increased weight gain regardless of temperature or sex. Interestingly, no HFHS-induced weight gain differences were observed between females at different temperatures. In contrast, 30{degrees}C male mice on HFHS gained [~]50% more weight than 20{degrees}C males, and [~]80% more weight compared to 30{degrees}C females. HFHS increased fat mass across all groups but 2-fold higher gains occurred in 30{degrees}C mice compared to 20{degrees}C mice. Females gained [~]35% less fat mass than males at both temperatures. ConclusionsTogether, these data reveal an interaction between divergent ambient temperature-induced EE and sex that impacted diet-induced patterns of short-term weight gain and body composition. HighlightsO_LIUtilized ambient temperature differences as an experimental tool to study the impact of divergent baseline energy expenditure on metabolic adaptation to high-fat, high-sucrose diet. C_LIO_LIBaseline energy expenditure and sex interact to impact diet-induced changes in body composition and weight gain. C_LIO_LIThe energy expenditure and sex interaction is a result of an inverse relationship between fat mass gain and weight-adjusted total energy expenditure, as well as, diet-induced non-shivering thermogenesis. C_LIO_LIThese data support that the hypothesis that higher energy expenditure amplifies the coupling of energy intake to energy expenditure during energy dense feeding, resulting in reduced positive energy balance and reduced gains in weight and adiposity. C_LIO_LIFirst evidence that energy expenditure level plays a role in the composition of weight gained by female mice during acute HFHS feeding. C_LIO_LIThis study further highlights issues with obesity/energy metabolism research performed in mice at sub-thermoneutral housing temperatures, particularly with sex comparisons. C_LI GRAPHIC ABSTRACT O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=100 SRC="FIGDIR/small/840702v1_ufig1.gif" ALT="Figure 1"> View larger version (35K): org.highwire.dtl.DTLVardef@39eb69org.highwire.dtl.DTLVardef@8e564forg.highwire.dtl.DTLVardef@c46714org.highwire.dtl.DTLVardef@4b5898_HPS_FORMAT_FIGEXP M_FIG Legend: Male and female mice housed at 30{degrees}C had lower energy expenditure (EE) & energy intake (EI), while having greater energy balance (EB), during 7-day high-fat/high-sucrose (HFHS) feeding compared to male and female mice, respectively, housed at 20{degrees}C. However, female mice had lower EB compared to males at both housing temperature. Female mice housed at 30{degrees}C gained less weight than 30{degrees}C males but gained the same relative amount of fat mass during acute HFHS feeding. Interestingly, 20{degrees}C females gained the same amount of weight as 20{degrees}C males but gained primarily fat-free mass, while the males gained the same proportion of fat as 30{degrees}C males and females. C_FIG

physiology↗